OTV Magnetic Encoder Rings – Direct Replacements for RLS, with Full Customization
At OTV Sensing, we focus on delivering high‑performance magnetic targets for rotary encoders. Our products not only serve as direct, drop‑in replacements for popular encoder rings from established brands like RLS, but also offer deep customization in dimensions, pole pairs, and magnetic performance – helping you get the most out of your motion control system.
For the mainstream RLS encoder families, OTV Sensing has built a complete cross‑reference database, enabling 1:1 replacement or even optimized alternatives.
1. Overview of AksIM‑2 Encoders and MRA Magnetic Rings
The AksIM‑2 is a high‑performance, off‑axis absolute rotary encoder developed by RLS. Its key specifications are:
Type: Off‑axis absolute rotary encoder (non‑contact, low profile)
Resolution: 17 to 20 bits (up to 1,048,576 counts per revolution)
System accuracy (after self‑calibration): ±0.004° to ±0.020°, depending on the ring size
Sampling frequency: 18 kHz; max refresh rate 54 kHz
Communication interfaces: BiSS C, UART (asynchronous serial), SPI, PWM, SSI
Supply voltage: 4.5 V to 5.5 V
Operating temperature: –40°C to +105°C
Shock & vibration: 100 g shock, 80 g vibration
AksIM‑2 uses an axially magnetized multipole magnetic ring (the MRA series), which consists of a metal carrier bonded with a flexible magnetic rubber. Different readhead models (MB022, MB029, MB039, MB049, MB053, MB064, MB080) pair with rings of specific inner diameter (ID), outer diameter (OD), thickness, and mounting style.
For example, the MRA022HP ring matches the MB022 readhead, with an ID of 8 mm and OD of 21.5 mm. The MRA080BC ring matches the MB080 readhead, with an ID of 55 mm, OD of 80 mm, and thickness of 2.0 mm.
The nominal installation gap (ride height) between the readhead and the ring surface is 0.25 mm ± 0.20 mm for smaller sizes, or 0.2 mm ± 0.15 mm for larger ones. The ring surface must not be exposed to external magnetic fields exceeding 50 mT, as this could cause permanent damage.
2. Compatible Rings for the AksIM‑4 Series – Large Hollow Shafts & 21‑Bit Resolution
For applications that require a large through‑hole – such as large radar gimbals or medical imaging equipment – RLS introduced the AksIM‑4 series. OTV Sensing offers fully compatible replacement rings for this series as well.
Ring models: MRA115 (90 mm ID) and MRA150 (125 mm ID)
Resolution: Supports up to 21‑bit binary readout
Dynamic performance: Maximum speed 3,150 rpm, with excellent shock resistance (100 g)
3. Core Advantages of OTV Sensing Replacement Rings
3.1 Direct Drop‑in Replacement – No Mechanical Modifications
Our magnetic rings are 100% compatible with RLS MRA series in all critical parameters:
Outer diameter, inner diameter, and thickness
Mounting hole positions and diameters (countersunk or through holes)
Number of pole pairs and magnetization pattern (axial multipole, with identical pole pitch)
Installation gap requirements (0.2 mm to 0.45 mm)
This means that whether you are using an MB022 or an MB080 readhead, you can simply remove the original ring and install the corresponding OTV Sensing ring – without any mechanical or firmware changes.
3.2 Equivalent or Better Performance
We use high‑quality ferrite composite rubber materials and precise magnetization processes to ensure uniform magnetic field strength and tight pole‑width tolerances, meeting or exceeding original specifications. Our in‑house tests confirm that OTV Sensing rings achieve the same system accuracy as the original RLS rings.
By testing and comparing individual pole deviation, accumulated deviation, and other performance-related parameters, we have verified that our magnetic rings fully satisfy the compatibility requirements for RLS magnetic encoders.
3.3 Broad Product Coverage
OTV Sensing has already developed replacement models for all mainstream RLS MRA rings. The following table shows a direct cross‑reference:
| RLS Ring Model | Readhead | OTV Equivalent | ID/OD/Thickness (mm) | Primary Mounting |
|---|---|---|---|---|
| MRA022HP | MB022 | OTV‑MR022 | 8 / 21.5 / 5.4 | Press‑fit (P) |
| MRA029BC | MB029 | OTV‑MR029C | 10 / 29 / 2.0 | Countersunk (C) |
| MRA029GP | MB029 | OTV‑MR029G | 12.7 / 29 / 7.0 | Glue (G) |
| MRA039BC | MB039 | OTV‑MR039C | 20 / 39 / 2.0 | Countersunk (C) |
| MRA049BC | MB049 | OTV‑MR049C | 25 / 49 / 2.0 | Countersunk (C) |
| MRA049AF | MB049 | OTV‑MR049F | 25 / 49 / 3.9 | Flat‑bottom counterbore (F) |
| MRA049BG | MB049 | OTV‑MR049G | 34 / 49 / 2.0 | Glue (G) |
| MRA053BC | MB053 | OTV‑MR053C | 30 / 53 / 2.0 | Countersunk (C) |
| MRA053BG | MB053 | OTV‑MR053G | 40 / 53 / 2.0 | Glue (G) |
| MRA064BC | MB064 | OTV‑MR064C | 40 / 64 / 2.0 | Countersunk (C) |
| MRA064BG | MB064 | OTV‑MR064G | 51 / 64 / 2.0 | Glue (G) |
| MRA080BC | MB080 | OTV‑MR080C | 55 / 80 / 2.0 | Countersunk (C) |
| MRA080AF | MB080 | OTV‑MR080F | 55 / 80 / 3.9 | Flat‑bottom counterbore (F) |
| MRA080BG | MB080 | OTV‑MR080G | 64 / 80 / 2.0 | Glue (G) |
| MRA080DF | MB080 | OTV‑MR080DF | 68 / 95 / 4.9 | Flat‑bottom counterbore (large OD) |
Note: OTV suffix C = countersunk, F = flat‑bottom counterbore, G = glue‑mount, P = press‑fit.
3.4 Deep Customization – More Than Just Replacement
Our core strength also lies in flexible manufacturing. If you need non‑standard dimensions, special numbers of pole pairs, different mounting styles, or specific materials, we can respond quickly.
Customizable parameters include:
Dimensions: ID from 5 mm to 150 mm, OD up to 200 mm, thickness adjustable from 1.5 mm to 10 mm.
Number of pole pairs: From 8 to 128 pole pairs (cycles per revolution), meeting various resolution requirements.
Mounting styles: Countersunk (C), flat‑bottom counterbore (F), glue‑mount (G), press‑fit (P), screw‑mount (S), snap‑ring (R).
Carrier materials: Stainless steel, aluminum alloy, or engineering plastic.
Zero‑position marking: Engraving, laser marking, or special magnetic feature.
Special environments: Oil‑resistant or chemical‑resistant coatings available.
4. Applications & Customer Value
Typical applications include:
Collaborative robot joints (absolute feedback with AksIM‑2)
Precision rotary tables and direct‑drive motors
Medical equipment (CT scanners, surgical robots)
Aerospace servo systems
Semiconductor equipment (wafer handling)
Direct benefits of switching to OTV magnetic rings:
Cost reduction: 30% to 50% lower than original spare parts.
Shorter lead times: Common models in stock; custom designs delivered within two weeks.
Customization: A flexible solution when standard products do not meet your application requirements.
- Chip application experience: We have many years of product development experience in sensing applications based on Hall and magnetoresistive principles, and are well-versed in the requirements of mainstream chips such as iC-Haus ic MU series.
We invite you to contact us to co‑develop the optimal magnetic ring solution for your encoder system.
Appendix: Full Parameter Table for RLS AksIM‑2 Encoders & MRA Rings (Reference)
| Readhead | Matching Ring | ID (mm) | OD (mm) | Thickness (mm) | Moment of Inertia (kg·mm²) | Max Speed (rpm) |
|---|---|---|---|---|---|---|
| MB022 | MRA022HP | 8 | 21.5 | 5.4 | 0.36 | 10,000 |
| MB029 | MRA029BC | 10 | 29 | 2.0 | 0.75 | 10,000 |
| MB029 | MRA029GP | 12.7 | 29 | 7.0 | 1.0 | 10,000 |
| MB039 | MRA039BC | 20 | 39 | 2.0 | 2.3 | 10,000 |
| MB049 | MRA049BC | 25 | 49 | 2.0 | 5.5 | 9,500 |
| MB049 | MRA049AF | 25 | 49 | 3.9 | 13 | 9,500 |
| MB049 | MRA049BG | 34 | 49 | 2.0 | 4.8 | 9,500 |
| MB053 | MRA053BC | 30 | 53 | 2.0 | 7.4 | 7,500 |
| MB053 | MRA053BG | 40 | 53 | 2.0 | 5.9 | 7,500 |
| MB064 | MRA064BC | 40 | 64 | 2.0 | 15 | 6,000 |
| MB064 | MRA064BG | 51 | 64 | 2.0 | 11.4 | 6,000 |
| MB080 | MRA080BC | 55 | 80 | 2.0 | 32 | 4,700 |
| MB080 | MRA080AF | 55 | 80 | 3.9 | 74 | 4,700 |
| MB080 | MRA080BG | 64 | 80 | 2.0 | 12.8 | 4,700 |
| MB080 | MRA080DF | 68 | 95 | 4.9 | 114 | 4,700 |
Ring coding convention (for reference): Mounting type (C/F/G/P), Material (M/S), Accuracy grade (D/E), Zero marking (E/H/N). OTV Sensing supports free customization of all these combinations.
FAQ
1.Can OTV Sensing magnetic rings directly replace my existing RLS AksIM‑2 or AksIM‑4 encoder rings?
Yes, absolutely. Our magnetic rings are 100% compatible with RLS MRA series rings in all critical aspects: outer/inner diameter, thickness, mounting hole positions, number of pole pairs, magnetization pattern, and installation gap (0.2 mm to 0.45 mm).
2.Will switching to OTV Sensing rings affect encoder accuracy or system performance?
Performance is equivalent. We use high‑quality ferrite composite rubber and precision magnetization to achieve uniform field strength and tight pole‑width tolerances.
3.What is the standard MOQ for your magnetic rings?
We are flexible to discuss volume-based adjustments for prototype or trial orders.
4.Can you produce custom desgin samples before full production? Is there a charge?
Yes, we can provide custom designsamples for validation. Samples are typically charged at a nominal fee to cover material and setup costs. Lead time for sample building is generally 4 weeks after design confirmation.
5.What is the typical lead time for standard magnetic ring orders?
For standard products with no stock, the lead time is 2 weeks after order confirmation and receipt of deposit.
6.Can you customize magnetic rings for non‑standard dimensions, pole pairs, or special mounting requirements?
Yes,we fully support customization for parameters such as inner/outer diameter, mounting hole positions, thickness, and magnetic properties to meet specific application needs.